Casing for a wellbore that has just been drilled is assembled at the surface as joints are added and the string is lowered into the wellbore. As the joints are added at the surface on the rig floor, it is desirable to fill the casing. Filling the casing before it is run into the wellbore prevents pressure imbalances on the casing as it is being advanced into the wellbore. Additionally, once the casing is filled, it may be desirable to circulate through the casing as it is being run into the wellbore. Devices used in the past are illustrated in U.S. Pat. Nos. 5,735,348 and 5,971,079.
The devices illustrated in these patents provide the means of filling and circulating the casing but do not address the issue of handling high-pressure circulation or control of the well since the force caused by high-pressures can buckle the pipe member holding the circulator in place or exceeding the load limit of the hoisting system, bails or elevator supporting the casing. In addition when the casing is filled, the seal will not allow the air trapped in the casing to escape. This results in pressurizing the casing as each section is filled. This results in well fluid (normally mud) being expelled when the seal is removed from the casing resulting in a dangerous eruption of mud and air which can injure personnel, damage equipment or cause environmental damage. Additionally, there is no method of isolating pressure from the rig mud system or allowing a high-pressure connection to be made other than the rig system and there is also no means to access the wellbore by wireline, coiled tubing or other means.
Accordingly, it is an objective of one configuration of the present invention to provide a means of isolating the high load from the pipe member holding the circulator in place or the hoisting system, bails and elevator supporting the casing. In addition, the seal will not be energized during normal filing operations, which will prevent pressurizing the casing as each section is filled. It is another objective of the present invention to provide a method of isolating the high-pressure, which may be used to circulate or control the well from entering the rig piping system. In addition a method is disclosed for controlling the pressure in the casing while providing a means of connecting a high-pressure mud system to the casing. A method is provided of disconnecting the rig hoisting system to provide access the wellbore. Another objective of the present invention is to provide additional means of sealing between the casing and circulator and to provide access to the wellbore by wireline, coiled tubing or other means.
In yet another configuration of the invention a means of sealing between the casing and the assembly is disclosed whereby flow of mud (flow-back) from the well can be routed to the rig mud system while each section of casing is lowered into the well. In this configuration it is possible to provide a means of setting the anchor system should the pressure in the casing exceed a pre-set value. In this configuration the apparatus disclosed can also be set remotely by use of a control system near or on the rig floor.
The invention allows a safe method of handling high-pressure that is a more environmentally friendly way of filling and circulating a casing as it is being run in the well.